The subject invention is directed to a device used to measure fluid levels, and more particularly, to dipsticks used to measure fluid levels by immersing an indicator at one end of the dipstick into a fluid holding compartment.
With internal combustion engines, transmissions, and other machinery requiring fluids for lubrication and cooling, it is known to use a fluid measuring device for indicating the fluid level in a selected fluid holding compartment. Typically, the fluid measuring device is a dipstick for checking the level of fluid such as engine or transmission oil, or hydraulic fluid within one of the many fluid holding compartments in the engine, transmission, or other machine. The dipstick is normally an elongated indicator that is slidably located within a conduit or pipe attached to the engine, transmission, or machine in which a fluid level indication is desired. When the dipstick is fully inserted into the conduit, one end is immersed into the fluid. When an actual reading of the fluid level is desired, the other end of the dipstick is pulled from the conduit thereby removing the entire dipstick from the conduit to allow the user to read the fluid level from the one end. The dipstick is then reinserted into the fluid compartment once the fluid level has been checked.
Traditional fluid level indicator systems typically consist of a two piece system with a holding tube and a dipstick. The holding tubes are generally fabricated from metal tubing and require various forming operations including bending, flaring, and machining, followed by the attachment of a dipstick receptacle. In addition, the dipstick is fabricated from multiple components including a handle, washer, cap, rubber stopper, shaft assembly, and a marked spring steel shaft mechanically joined to a spring steel blade. The actual assembly of these various components involves multiple assembly operations requiring costly, time-consuming, and labor intensive manufacturing steps. Therefore, a simpler design requiring fewer parts and connections as well as less forming is desirable.
In addition, today""s engines, transmissions, and machinery designs are smaller, more compact, and of less weight than traditional engines, transmissions, and machinery. Therefore, fluid level indicator systems must be smaller, more compact, and lighter weight. Moreover, the fluid access routes or paths through which the fluid level indicator system accesses the fluid storage compartments are becoming more complex (more twists and turns as well as longer runs), smaller, and more compact. The result is a need for smaller and lighter weight fluid level indicator systems with improved flexibility.
It is also desirable to provide a fluid level indicator system allowing access to the fluid compartment while assuring a secure, sealed closure of the access when fluid level determinations are not being made and/or additional fluid is not being added. This sealed closure would prevent unnecessary loss of the fluids during operation as well as supply level pressurization. Moreover, a positive indication that the dipstick is securely in place is desirable.
This invention represents an improvement over the presently-known dipsticks which measure fluid levels when immersed in a fluid compartment.
The fluid level measuring device includes a stationary tube assembly extending from the fluid compartment in which a dipstick is disposed. The dipstick includes a plastic handle that is directly joined or molded to one end of a flexible shaft, such as a spring steel wire shaft. A precision stamped fluid level indicator blade extends from a second end of the shaft and is preferably attached to the flexible shaft by either die casting, spin welding, ultrasonic welding, or other, bonding means, or by means of a fitting or other connector. The tube assembly is preferably made of a plastic material with an enlarged end. Lugs extend from the end and provide a bayonet interconnection between the tube and the handle assembly by twisting the handle assembly relative to the tube. This causes interengagement of the lugs with slots in the handle. A steel engine fitting extends from the tube and serves to guide the indicator blade to an appropriate location within the fluid cavity.
A gasket acts as a pressure lock seal for sealing the handle to the enlarged end when the lugs are locked in the slots. This pressure lock seal serves to allow significant pressurization within the dipstick and oil pan or other chamber the dipstick is affixed to.
The bayonet interconnection in unison with the gasket supplies an actual pressurized seal not found in any of the prior art assemblies, thereby allowing pressurized testing of the combustion engine, transmission, or other machinery without either removal of the dipstick or attempts at sealing the dipstick. Furthermore, a sealed dipstick allows the combustion engine, transmission, or other machinery to run at the intended pressure rather than either below the intended pressure or at the intended pressure due to an adjustment.
The structure is manufactured from lightweight, corrosion-resistant, plastic materials with the exception of the flexible metallic shaft, attachment fitting, blade, and metal engine fitting. The seal and locking engagement between the handle and enlarged end preferably involves a quarter-turn sealing motion with an improved sealing capability and a positive lock feature.
It is an object of the invention to provide a fluid level indicating system capable of being in fluid communication with the combustion engine, transmission, or other machinery to which it is affixed while maintaining a constant pressurization therein through an improved method of sealing. Specifically, a seal that is capable of maintaining several atmospheres (at least 1 to 1.5 atm.) of back pressure is desirable.
It is another object of the invention to provide a positive engaging, yet easy to use, locking arrangement for securely locking and sealing the dipstick within or over the tube with an easy motion. It is also desirable that this sealing of the dipstick within the tube is such that the tube may be pressurized to the same back pressure as the combustion engine, transmission, or other machinery.
It is still a further object of the invention to provide a smaller and more compact fluid level indicating system which has improved flexibility for routing of the fluid level indicator system in and around the complex design of today""s engines, transmissions, and machinery.
In addition, it is yet another object of the invention to provide a more corrosion-resistant, lighter weight, less complex, higher precision and more cost effective fluid level indicator system.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.